Musica Pristina’s Virtuoso Network DAC is a Roon Ready DAC that takes advantage of Roon Lab’s RAAT (Roon Advanced Audio Transport) protocol technology for bit perfect network streaming over Ethernet and WiFi networks. RAAT supports “all relevant audio formats today and for the foreseeable future.” Musica Pristina is one of the earliest companies to support Roon’s RAAT with a DAC that utilizes this new network protocol.

To take advantage of the Roon Ready feature of the Virtuoso Network DAC, you will need a subscription to the Roon Music Management Player that runs from a computer supporting Windows, OSX, Linux (x86) or NAS storage supporting QNAP x 64 NAS(qpkg) or Synology x 64 NAS(spk).

One obvious missing feature on the Virtuoso Network DAC is the absence of a USB input. Musica Pristina feels that Ethernet based audio is superior to USB for transmitting digital audio data. They also feel that USB audio playback is a flawed modality exemplified by the plethora of USB enhancement devices that are offered today to deal with USB audio’s shortcomings.

The Virtuoso Network DAC is a relatively large device that has an attractive aluminum faceplate with only two front panel controls besides the power switch: one is for selection of the 4 inputs, while the other is a volume control. The volume control on the Virtuoso features an analog discrete resistor stepped shunt attenuator. There is a switch on the back of the Virtuoso for selection of either single-ended or balanced outputs. That’s about it; no fancy LED display, filter selectors, or other non-essential features.

The following are some of the highlights of the Virtuoso Network DAC design:

All inputs are galvanically isolated from the DAC board. A pair of Burr-Brown 1794 DAC chips performs the digital to analog conversion. The current output of the DAC chips is passively converted to voltage by an array of tantalum resistors.

The Virtuosos Network DAC features dual mono D/A circuitry with dual mono analog circuitry each fed by its own current regulated power supply. I was surprised to see a differential vacuum tube (6H30P) gain stage with its own integral power supply. The power for the digital section of the DAC is separate from that of the analog section. The analog section features 10 individual regulators, each with its own purpose.

This DAC also has a fully balanced signal path with the output circuits being transformer coupled for both the RCA and XLR connectors. The “XLR/RCA“ switch provides the option for grounding the negative outputs of both connectors, thus providing unbalanced (or “single-ended”) outputs.

photo credit: Musica Pristina

The Design of the Virtuoso Network DAC
The two men behind the design of the Virtuoso Network DAC are Kevin Welsh and Dave Davenport. Kevin is a software designer who did the processor board, i2s driver, and operating system work. Dave is the hardware engineer who developed the Virtuoso Network DAC. I asked Kevin and Dave to provide us with some in-depth background of the Virtuoso Network DAC’s design:

A lot goes into the design; the main points worth emphasizing here are:

Fully balanced design

Elimination of external ground loops

Internal isolation

Dual mono

Power supply structure

Voicing the circuit

Selection of components

Choosing operating points

Network DAC

Fully balanced
Everything – from the output of the DAC chip, through the differential amplifier, to the transformer-coupled output – is fully balanced circuitry.

Elimination of external ground loops
All external inputs and outputs are galvanically isolated with transformers, thereby completely eliminating any possibility of ground loops.

Internal isolation
The internal isolation in the Virtuoso is carefully controlled by two factors: dual mono design and power distribution structure.

The design of the Virtuoso incorporates two separate audio channels starting in the first possible place – two separate DAC chips operating in mono mode. Then the signals pass through two separate amplifiers, each with its own power supply. This provides optimal isolation between the two channels.

Power is carefully structured such that current sources and returns only flow where they are used – there is no mixing of internal ground currents. To provide maximum internal isolation, the unit has six separate power supplies, two of which power the DAC board.

Voicing the circuit
Interestingly, we find that price and specifications don’t accurately determine which component will sound best in a given application. The technical design generates a list of potential components. Then, each of those is evaluated (by listening), and ultimately one is chosen. For example, six different types of resistors are used in the differential amplifier – each chosen for its performance in different parts of the circuit.

It doesn’t stop here. We spent over 100 hours selecting the operating point for the tubes—adjusting the current in small increments and listening for the best result. Once several “sweet spots” were found, we’d adjust the bias in small increments and listen again for the results. When the best bias points were found, we’d re-evaluate the previously selected current points.

Network DAC
In addition to the typical functions you’d find in nearly any DAC, the Virtuoso Ethernet DAC also features a built-in Roon endpoint, implemented with a processor board and customized software. Voicing the software, if you will, followed the same logical progression. The processor board, selected from a set of about a half dozen, was chosen for its sonic performance. We wrote the I2S driver to complement the DAC. Even the operating system itself has been evaluated and enhanced to best serve the purpose of running Roon and clocking the Roon Advanced Audio Transport (RAAT) signal into the DAC board. Of course, the processor board is galvanically isolated as well.

Why no USB input or DSD processing?
The purpose of the Virtuoso Network DAC is to provide the best possible musical listening experience, which we believe is obtained through network streamed audio over Ethernet. USB is an inferior audio interface, as evidenced by the constant attempts of manufactures to fix its inherit problems.

We didn’t set out to build a one-size-fits-all solution. We aimed to develop a device that creates the best listening experience possible. Contemplating DSD required a difficult decision: either we would need to develop a multi-purpose output stage that diminishes our PCM presentation, or we would need to use a multi-purpose DAC chip that also weakens our PCM presentation. (I suppose we could have used 2 different chips and 2 different output stages, but then it would have been two different DACs, wouldn’t it?)

At the end of the day, and after sonically evaluating many chip options, we decided to adopt a PCM output based on the Burr-Brown PCM1794. It’s not that we think DSD is inherently better or worse, we just decided to hone our PCM-only implementation. Of course, anyone with DSD material can convert it on the fly in Roon for playback through the Virtuoso – and it still sounds amazing.

Software Updates For The Virtuoso Network DAC
We run a tiny web server that offers up a configuration page. It has your registration details, our contact information and a button you can click to get firmware updates on demand.

The Roon Core and Associated Components
I employed my Asus G501 JW laptop running Windows 10 Pro 64 to run Roon Server and act as my Roon Core to stream to the Virtuoso Network DAC. The Asus G501 JW possesses an Intel Core i7 4720HQ 2.6 GHz processor with 16 GB RAM and a very fast PCE Express X4 SSD. This laptop has 3 USB 3.0 ports as well as a Thunderbolt port. The Asus laptop was plugged into a Shunyata Research Hydra DPC-6 v2 distribution center to firewall the noise generated by this computer from contaminating my AC line.

The Core was remotely controlled by an iPad Air 2 that replicated all of the functions of the standard Roon program.

The Asus was placed on a Synergistic Research Tranquility Base UEF grounded with the Synergistic Research High Definition Ground Cable / Grounding Block as was the computer. Two 8 TB GRAID Thunderbolt drives were connected; one for PCM and the other for DSD files. AudioQuest Coffee Thunderbolt cables were used. The GRAID Thunderbolt drives were powered by HDPlex 100w linear power supplies plugged into the Shunyata Hydra DPC-6 ver 2. The GRAID Thunderbolt drives and their HDPlex power supplies were placed on a Synergistic Research Tranquility Base.

I found that selecting an upgrade Ethernet cable could enhance the sound of the Virtuoso Network DAC. Excellent sonic results were obtained with an AudioQuest Diamond Ethernet cable. I also had very good results with the AudioQuest Vodka, but the Diamond did elicit the best performance from the Virtuoso Network DAC.

The Virtuoso Network DAC was powered from a Shunyata Triton v2 / Typhon power conditioner using a Shunyata Alpha AC cord.

I tried different footers under the Virtuoso with my final selection being Ayre Myrtle wood blocks. These were inexpensive and effective in improving the sound over the rubber feet found on the Virtuoso Network DAC.

Once the DAC was turned on with its 35-second delay relay, Roon recognized the Virtuoso Network DAC allowing one to select it as the output device. Roon and the Virtuoso Network DAC worked flawlessly together.

photo credit: Musica Pristina

The Virtuoso Network DAC Sound
My friends often comment to me that they don’t hear a great difference between a $2000 DAC and the DACs over $10,000. DAC design has vastly improved since I began my quest in 2006 to find a musical DAC that would supersede my vinyl rig. Today we have DACs that are enjoyable to listen to for extended periods of time under $2000. But I contend that something is missing from these DACs; something I have experienced with the best DACs I have reviewed and something I heard using the Virtuoso Network DAC.

The Virtuoso Network DAC has the ability to reproduce musical instruments and voices with the weight and substance of the real thing. There is no thinness or sense of compression to the sound when listening to the Virtuoso. This acoustically rich and substantive sound is reproduced with a soundstage that is wide and deep with the ability to recreate the recorded acoustic space.

The Virtuoso has a slightly full midbass, but it is articulate and well defined as is the deep bass. Voices and instruments are reproduced without digital hardness or over etched definition. The high end is beautifully rendered with wonderful detail and focus.

Both macro and micro dynamic changes are well served by the Virtuoso Network DAC. This DAC is extremely revealing with outstanding resolution if the source fed to it is top-grade. Those of you that miss their analog vinyl rig when listening to digital music will, without question, love the Virtuoso Network DAC.

Background silence was exemplary listing to orchestral and acoustic music with never a hint of tube noise from the Virtuoso’s vacuum tube (6H30P) gain stage.

Some of you will be turned off by the fact that the Virtuoso Network DAC cannot directly play DSD files. But I did find that Roon was very effective in converting my .dsf files to 176.4 kHz output that was quite good sounding.

I don’t want anyone to get the impression that the Virtuoso Network DAC has such a strong “personality” that everything it plays sounds beautiful. This is not the case. Poor recordings still sound lousy, but superior sounding recordings will sound exceptionally real and involving.

The Virtuoso Network DAC and the Music
One terrific recording I have recently heard is Polly Gibbons’ Many Faces of Love (24/48). This contemporary jazz recording does a wonderful job of highlighting Gibbon’s voice accompanied by a group of first-class musicians. Gibbon’s voice has excellent focus and definition with an ease that makes it sound like she is in the room. The Virtuoso Network DAC was able to reproduce the transient detail of the piano, guitar, bass, and drums with a life-like sense of instrumental body and weight.

The Virtuoso Network DAC is able to handle prominent bass with transient impact and definition. Playing Fourplay, Fourplay’s debut recording (24/96), displayed the Virtuoso network DAC’s ability to easily handle the challenge provided by this recording. Nathan East’s bass had outstanding extension and dynamics with immediacy and palpability. When called upon, the Virtuoso was able to deliver the rhythmic drive of this recording while preserving the fine nuances of Bob James’ keyboard work and Lee Ritenour’s guitar.

Enthusiasts of classical music will love the Virtuoso. Vivaldi: L’Estro Armonico with Rachel Podger / violin and the Brecon Baroque (24/192) is an example of string music that I enjoyed listening to. The recording was reproduced with lifelike timbres and textures. The inner detail and resolution of this recording allowed the Virtuoso to deliver a dynamically expressive sound. The acoustics of the Crystal Palace in London England were captured with outstanding air and bloom around the instruments.

photo credit: Musica Pristina

A Perfectionist DAC
The Virtuoso network DAC is a perfectionist product that focuses on musical performance. The Roon Ready feature of the Virtuoso network DAC ensures ease of setup and function with a first-class software and software remote control. The superb sound quality of the Virtuoso Network DAC places it in the special category of audiophile DACs that possess liquidity and a natural richness in the reproduction of music.

I wonder how the Virtuoso DAC was able to capture the acoustics of the Crystal Palace in Rachel Podger and Brecon Baroque's recording of Vivaldi; L'Estro Armonico? The location was destroyed by fire in 1936.

I think there is some confusion. The recording was made in Upper Norwood. Crystal Palace ( not The Crystal Palace) is a South London district part of which is in Upper Norwood. The acoustic captured is that of St. John the Evangelist church.

"They also feel that USB audio playback is a flawed modality exemplified by the plethora of USB enhancement devices that are offered today to deal with USB audio’s shortcomings."

While USB's foibles are pretty obvious, using the plethora of devices as proof does not quite wash. USB is used much more for audio presently so it is inevitable that would also generate more devices to fix its problems. It seems likely the same may happen if Ethernet gains ground unless they are correct, in which they may be, but I do not see an explanation that convinces so far. This is reminiscent of the fallacy that Macs can't get viruses. They can, there are just fewer viruses written targeting Macs to date because Macs had been in the minority until they started to gain sales ground lately. That is likely to change this perception as well.

USB certainly has a serious flaw for audio in that it sends packet of information, i.e. chopped up information that then has to be reassembled smoothly. Plenty of room for trouble there alone. This is why I use eSATA where I can, myself. But Ethernet also sends packets of information with that same issue likely. Your finding that an upgrade cable sounds better:
"I found that selecting an upgrade Ethernet cable could enhance the sound"
also suggests that Ethernet may have pretty much the same issues.

I have not used Ethernet for audio myself yet so I do not have an opinion on the matter but would like to know more about this. So could you, or anyone else seeing this, please explain what it is about Ethernet that makes it better than USB for audio? TIA for the information.

No, Ethernet & USB have not same issues. USB carries data along with Vcc +5V that makes digital signal dirty. That's why you see isolation implemented in many morden USB DACs or you have to feed pure Vcc +5v (iFi USB power) to have a sound good. Last but not least, the data going in USB cable is already dirty on the way to USB DAC so can't compare with Ethernet which was isolated itself.
You can easily find yourself an answer by switching a/b between USB and Ethernet cables feeding the same DAC such as Marantz. NA11s1, NA8005, Ps PWD with Bridge etc. Good luck!

For me the well known dirty Vcc makes no difference since all my USB connected items are Vcc isolated - I inject my own (hand built) clean power and do not need the aftermarket solutions, which are available easily enough from a number of manufacturers anyway. I build fine USB cables that do this, the only ones AFAIK on the market that offer this option so I can do this right at the cable or with an adapter I also build. I also separate the data and power lines under separate shields within additional combined outer shields. So I do not even consider this in the comparison, its a solvable issue. That leaves the matter of both systems sending packetized information that then has to be reassembled. That is where I see the worst issues in USB. Since Ethernet does the same thing, I am still looking for where this superiority is purported to be. I can see this may be conveniently solved for folks that don't do anything about the dirty power but the far more important issue of getting the information properly reassembled seems to be the same without significant superiority so far as I can see unless there is something about that process that gives Ethernet an edge? Otherwise this would comes down to just a matter of convenience with neither being ultimately superior sonically after the power issue is dealt with. Do you know of any other reason to consider Ethernet to be superior - sonically - aside from the dirty power?

Switching between the two in my systems is not likely to produce a difference on that basis.